diagramitem.cpp Example File

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  #include "diagramitem.h"
  #include "arrow.h"

  #include <QGraphicsScene>
  #include <QGraphicsSceneContextMenuEvent>
  #include <QMenu>
  #include <QPainter>

  DiagramItem::DiagramItem(DiagramType diagramType, QMenu *contextMenu,
               QGraphicsItem *parent)
      : QGraphicsPolygonItem(parent)
  {
      myDiagramType = diagramType;
      myContextMenu = contextMenu;

      QPainterPath path;
      switch (myDiagramType) {
          case StartEnd:
              path.moveTo(200, 50);
              path.arcTo(150, 0, 50, 50, 0, 90);
              path.arcTo(50, 0, 50, 50, 90, 90);
              path.arcTo(50, 50, 50, 50, 180, 90);
              path.arcTo(150, 50, 50, 50, 270, 90);
              path.lineTo(200, 25);
              myPolygon = path.toFillPolygon();
              break;
          case Conditional:
              myPolygon << QPointF(-100, 0) << QPointF(0, 100)
                        << QPointF(100, 0) << QPointF(0, -100)
                        << QPointF(-100, 0);
              break;
          case Step:
              myPolygon << QPointF(-100, -100) << QPointF(100, -100)
                        << QPointF(100, 100) << QPointF(-100, 100)
                        << QPointF(-100, -100);
              break;
          default:
              myPolygon << QPointF(-120, -80) << QPointF(-70, 80)
                        << QPointF(120, 80) << QPointF(70, -80)
                        << QPointF(-120, -80);
              break;
      }
      setPolygon(myPolygon);
      setFlag(QGraphicsItem::ItemIsMovable, true);
      setFlag(QGraphicsItem::ItemIsSelectable, true);
      setFlag(QGraphicsItem::ItemSendsGeometryChanges, true);
  }

  void DiagramItem::removeArrow(Arrow *arrow)
  {
      int index = arrows.indexOf(arrow);

      if (index != -1)
          arrows.removeAt(index);
  }

  void DiagramItem::removeArrows()
  {
      foreach (Arrow *arrow, arrows) {
          arrow->startItem()->removeArrow(arrow);
          arrow->endItem()->removeArrow(arrow);
          scene()->removeItem(arrow);
          delete arrow;
      }
  }

  void DiagramItem::addArrow(Arrow *arrow)
  {
      arrows.append(arrow);
  }

  QPixmap DiagramItem::image() const
  {
      QPixmap pixmap(250, 250);
      pixmap.fill(Qt::transparent);
      QPainter painter(&pixmap);
      painter.setPen(QPen(Qt::black, 8));
      painter.translate(125, 125);
      painter.drawPolyline(myPolygon);

      return pixmap;
  }

  void DiagramItem::contextMenuEvent(QGraphicsSceneContextMenuEvent *event)
  {
      scene()->clearSelection();
      setSelected(true);
      myContextMenu->exec(event->screenPos());
  }

  QVariant DiagramItem::itemChange(GraphicsItemChange change, const QVariant &value)
  {
      if (change == QGraphicsItem::ItemPositionChange) {
          foreach (Arrow *arrow, arrows) {
              arrow->updatePosition();
          }
      }

      return value;
  }